title: Using microbubbles as an MRI contrast agent for the measurement of cerebral blood volume.
abstract: The susceptibility differences at the gas-liquid interface of microbubbles (MBs) allow their use as an intravascular susceptibility contrast agent for in vivo MRI. However, the characteristics of MBs are very different from those of the standard gadolinium-diethylenetriaminepentaacetic acid (Gd-DPTA) contrast agent, including the size distribution and hemodynamic properties, which could influence MRI outcomes. Here, we investigate quantitatively the correlation between the relative cerebral blood volume (rCBV) derived from Gd-DTPA (rCBV(Gd)) and the MB-induced susceptibility effect (ΔR(2*MB)) by conventional dynamic susceptibility contrast MRI (DSC-MRI). Custom-made MBs had a mean diameter of 0.92 µm and were capable of inducing 4.68 ± 3.02% of the maximum signal change (MSC). The MB-associated ΔR(2*MB) was compared with rCBV(Gd) in 16 rats on 4.7-T MRI. We observed a significant effect of the time to peak (TTP) on the correlation between ΔR(2*MB) and rCBV(Gd), and also found a noticeable dependence between TTP and MSC. Our findings suggest that MBs with longer TTPs can be used for the estimation of rCBV by DSC-MRI, and emphasize the critical effect of TTP on MB-based contrast MRI.
authors.affiliation: Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Shin-Lei
authors.initials: SL
authors.lastname: Peng
authors.forename: Fu-Nien
authors.initials: FN
authors.lastname: Wang
authors.forename: Chung-Hsin
authors.initials: CH
authors.lastname: Wang
authors.forename: Hsu-Hsia
authors.initials: HH
authors.lastname: Peng
authors.forename: Chih-Tien
authors.initials: CT
authors.lastname: Lu
authors.forename: Chih-Kuang
authors.initials: CK
authors.lastname: Yeh
mesh_terms: D000818:Animals; D001810:Blood Volume / Q000502:physiology*; D001811:Blood Volume Determination / Q000379:methods*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003287:Contrast Media; D019786:Gadolinium DTPA; D008279:Magnetic Resonance Imaging; D008297:Male; D045423:Microbubbles; D051381:Rats; D017207:Rats, Sprague-Dawley; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA
keywords: DSC-MRI; cerebral blood volume; microbubbles; time to peak